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Journey through nearly 14 billion years of history with the Big History Project, now available on Khan Academy. This course asks the big questions about our Universe, our planet, life and humanity. Examine our shared history across scales and disciplines. From the Big Bang to our still expanding universe, this course, created and maintained by the Big History Project, will lead you on a journey of astounding connections and exciting discoveries.

Just 500 years ago, humans lived in four separate world zones, each with distinct cultures and technologies. Now, humanity is linked within one interconnected network of information and commerce that spans the entire planet.

For most of the agrarian era, the four world zones operated independently of each other with little or no knowledge of what was going on in the other zones. The world, in effect, was divided into four unconnected regions, none of which was really interested in the others. With the improved transportation and communication technologies developed 500 years ago, humans acquired the means for connecting these formerly independent zones. After 1492, for example, the Americas and Afro-Eurasia were put in regular contact, and the Columbian Exchange saw the transfer of people, ideas, animals, plants, and diseases between these two once separate world zones. Exchanges like these fueled social, political, economic, and intellectual innovation. Within a few hundred years, this more fully connected world saw dramatic acceleration in innovation and population growth, which ushered in the Modern Revolution.

For most of the past 10,000 years or so, the biosphere has been a fairly stable and predictable place. Whether you look at temperature, types of vegetation, soils, or sea level, the basic characteristics of the biosphere have remained about the same, having shown only moderate variation at any point within most of that time frame. That type of consistency is what prompted geologists to label the last 10,000 years of geological history as the Holocene Epoch; an epoch that was ushered in at the end of the last ice age. But there are now a number of scientists who view the data from the last 250 years and conclude that the biosphere is showing fundamentally different characteristics from the previous 10,000 years. The rise of carbon dioxide levels, glacial melting, and the shrinking of tropical rainforests are just some of the factors that they cite as evidence that the biosphere has entered a new epoch. Because so much of the change they have identified seems to derive from human activity, these scientists propose that this new epoch be called the Anthropocene to reflect the tremendous impact that humans now exert in the biosphere.

The Modern Revolution created the world we live in today. This world is very different from the world of 500 or 1,000 years ago, let alone 10,000 or 100,000 years ago. The connection of the four world zones allowed for the creation of a global network of exchange. Though this network was not built overnight, it emerged fairly quickly, and it increased the potential connections and diversity of connections for many members of the network. The result was an acceleration of both collective learning and innovation. Commerce was an important driver of change in this global network. Because commerce began to take on greater significance for many societies, a number of important thinkers began to ask questions about the nature of the exchange of goods, the nature of productivity and efficiency, and the interests of the individual and the state in business. All of this new inquiry gave birth to the discipline of economics. These economic thinkers, like the thinkers in any discipline, shared a set of concerns and questions but often came up with very different answers to those questions. The articulation of the ideas of capitalism and communism were the most influential economic ideas generated in the course of the Modern Revolution.